Ray Allen scored 51 points, converting a team playoff record nine 3-pointers, including one to tie the score, 118-118, sending things to a third overtime.
The Celtics lost three starters - Glen Davis, Kendrick Perkins, and Paul Pierce - to disqualifications, and squandered chances to make an improbable rally in the final OT.
Brad Miller provided the deciding point with a free throw with 28.3 seconds remaining. The Celtics cut the deficit to 1 as Rajon Rondo followed his own miss 4.6 seconds later. Then the Celtics had two chances to recover. After Kirk Hinrich missed a layup on an inbounds play, the Celtics called time out with 16.7 seconds to go. Derrick Rose blocked Rondo's shot, then was fouled by Brian Scalabrine with 3.2 seconds on the clock. Rose missed both free throws, and Rondo launched a shot off the backboard at the buzzer.
The Celtics had seemed on the verge of concluding the series with an 18-point run over a five-minute span late in regulation. But they squandered a 99-91 advantage, Miller providing the tying points on a 3-pointer with 1:06 remaining and a layup with 29 seconds left.
"With an 8-point lead, if you're a good defensive team, all you have to do is play defense," Celtics coach Doc Rivers said. "You don't have to score again. You literally don't have to score again. But we didn't do that.
"We just stopped playing. We had a chance to close it out. We saw that score and we just stopped playing. Give them credit, they made a lot of big shots. Brad Miller was their savior. The 3-point shot we should have never given up, that was our breakdown, then the drive. I thought those were the two biggest plays because it gave them hope again, and it was too quick. He was the hero of the game.
"We let a team shoot, again, close to 50 percent against us. We're supposed to be a defensive team - we've got to be better defensively. I know we scored 127 points; that's dandy. But if we're going to win, we're going to win with our defense."
Game 5 (a 106-104 Celtics win in OT) was decided on a late play involving a hard foul by Rondo on Miller. This contest started out with an altercation involving Hinrich and Rondo. And Pierce took a hit that required stitches in his nose in the third quarter.
